Overlapping cam action



4 Sheets-Sheet 1 wjH, JOHNSON OVERLAPPING CAM ACTION Filed June 18, 195e May 23, 1939.

May 23, 1939. w. H- JOHNSON OVERLAPPING4 CAM ACTION Filed June 18, 1956 Y 4 Sheets-Sheet 2 ATTORNEY May 23, 1939 v w.\H. JoHNsoN 2,159,739

OVERLAPP ING CAM ACTION May 23, 1939. w. H. JoHNsoN.

OVERLAPPING CAM ACTION Filed June 18,1936 4 sheets-sheet 4 nu.. i

' v ATTORNEY/' M Patented May 23, 1939 UNITED STATES PATENT OFFICE 2,159,739 ovERLAPPING cAM ACTION William Horace Johnson, Cranston, R. I., assignor toWeskenson Corporation, Providence, R. I., a corporation ofvRhode Island Application June 18,

1 Claim.

ably mounted for relative rotation. The high and low points of the cam surface may be soy arranged with respect to the position of the followers that yeach follower in riding from its lowermostposition to its uppermost position assumes itsload before the preceding follower has released' its load. `Thus, an overlapping or continuous cam i actionis obtained which eliminates any undesir- ,able effects due to lost motion.

`The cam surface may have anydesired circumferential configuration, `but `it has preferably a configuration of such shape as to impart vsubstantially uniform velocity to the shaft driven by the followers. 'I'he cam surface may have a flaring or `conical form so that, by axially shifting the cam drum and followers relatively, the throw of the followers, and consequently the speed of the driven shaft, may be changed by ini'lnitesimally small steps with constant speed of the drive shaft and consequently constant angular velocity of the followers relative to the cam. If desired-suitable annular steps may be `provided in the cam surface corresponding to predetermined most desirable speed ratios,

point with the low points in line and the, high points in line, the throw of the cam surface decreasing toward one end to a true circle having zero throw.

According to one embodiment of the invention, the special cam surface may be placed on the inside of a cam ring. Within this ring may be mounted a rotary casing to which the drive shaft is connected. The casing carries theplu'rality of 40 followers which roll on the cam surface. These followers may be pivoted on the drum and lthe drum may carry a plurality of planetary gears each having incorporated therein an overriding clutch operated by one of said followers. Also within the casing may be a driven gear meshing said planetary gears, to which the driven shaft is connected,` Speed variation may be obtained by axially shifting the cam ring.

i If desired, the overlapping cam action and infmitely Variable speed operation may be obtained by other types of cams, as for example, iiat cams and drum cams. In the case of a drum cam, the cam surface may `berthe outside of a drum attached to a driven shaft. The followers may be pivoted to the stationary housing. rIfhe oscillating motions of the followers may be applied through overriding clutches to transfer gears which in turn mesh with a driven gear attached to the Y driven shaft, The transfer' gear and driven gear "are `mounted on the stationary housing. Speed The circumferential con-1 guration of the cam is preferably similar at each 1936, serial No. 85,841

variation may be obtained by axially shifting the followers on their shafts.

This application is a continuation in part of application Serial No. 11,913, filed March 20, 1935. The invention also consists in certain new and original features of construction and combination of parts hereinafter v'setforth and claimed. ,Although the novelfeatures which are believed to be characteristic of` this invention will be particularly pointed `out inthe claims appended hereto, the invention itself, as to its objectsand advantages, and the manner in which it may be `carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which Eg, 1 is a vertical sectionthrough a transmission embodying the cam action according to the invention taken on the line I`I of Fig. 2;

Figs. '2a and 2b are sections taken on the lines 2a--2a and 2b42b`of Fig. 1; Y

Fig. 3 is adetail of the follower and overriding clutch mechanism taken on the fline 3-3 of Fig. 2a;

cam action;

Fig. 5 is a longitudinal section of a modified..

form of transmission;

Figs. 6a, and 6b are sections taken on the lines Ict--Bc'll and Blz-6b, respectively, of Fig. 5; and

Fig.I 7 is a diagrammatic view illustrating the cam action. Y i

In the ollowing description and in the claims, various details will be identified by specific names for convenience, but they are intended to be as generic in their application as the art will permit.

Like reference characters denote like parts in the several figures of the drawings.

In-the drawings accompanying and forming part of this specification, certain specific disclosure of the invention is made for purposes of explanation, but it will be understood that the details may be modified `in various respects without. departure from the broad aspect of the invention. 'v i 'Referring now to the drawings, and more particularly to Figs. 1-4, the transmission comprises a stationary housingV I0 having an annular body I I with detachable ends or heads I2 'and I3. The heads I2 and I3 may be secured to the body in any desired manner, as by suitable bolts. If desired, the housing may be filled to a suitable level with lubricant vfor lubricating the mechanism.

Mounted within the housing I0 is a casing I4 having a drum portion I5 and detachable heads IS and I'I secured thereto by bolts or in any other v desired manner. Head I6 issuitably secured to drive shaft I8 and is journalled in a ball bearing I9 `supported ina hub on'the end plate I2 of thehousing.` The head Il is provided with a hub which is journalled in a ball bearing 20 supported by a hub on the end plate I3 of the housing.

The driven shaft 2| is journalled by ball bear- 5 ing 22 in a hub on head I6 and by a ball bearing 23 in a hub on head I1. The driven shaft 2| carries a gear 24 which meshes a plurality of planetary gears 25 (see Figs. 2a and 2b) Journalled in the rotatable casing I4 are a plurality of oscillating shafts 21. Each shaft 21 (Fig. 3) is journalled by ball bearings 28 and 29 in suitable hubs on heads I6 and I1. Each shaft 21 carries a follower arm 30 which in turn carries a roller or wheel 3| which may be the outer race of a roller bearing whose inner .race is mounted upon shaft 32. The outer end of arm 30 is suitably forked and the shaftV 32 secured thereto.

Each .gear ismade hollow and has a hub 0 portion 38Ajournalled upon shaft 21 b-y a suitable ball'be'aring. Within the hollow gear 25 is a core or holder-34 secured to the shaft 21. The core 34j-has a series `of `tapered recesses 35 in which roll a series of rollers 36. Each roller 36 25` has a spring assembly 31 behind it which normally tends to wedge its roller in between the outer casing formed by gear 25 and the core 34. The gear 25 is provided with a bushing 39 suitably journalled on shaft `21 bya suitable ball l bearing forclosing the overriding clutch space and holding l'the clutch parts in position.

Mounted within the body II of the housing IIJ is a cam ring `-40'.V This cam ring is slidable longitudinally of the housing Vand is provided with as .diametrcally disposed pins 49 (Figs. 2a. and 2b) slidable 4in longitudinal slots in the 'body 'I I.

will be understood that suitable external devices (not'shown) will 'be provided for longitudinally moving the pins 49 axially of the housing I0 to 40 change the speed ratio as hereinafter explained A more in detail.

The circumferential configuration of the 'cam surface 'of the' cam 40 issimilarat each transverse section, but the ecc'entricity or throw of 45 the surface varies from the right hand 'end in 55 tween. These steps have similar annular char- .-.acteristics throughout the longitudinal extent of each step and are for the purpose of providing stable positions on which the rollers 3| may roll. It will be` understood that these steps are not 60 absolutely necessary, but are only'provided when ffspecial speed ratios are used more than any other. Referring again to Fig. 4, the circumferential conguration of the cam surface of cam 40 is of a special form to obtain constant angular ve- 65 locity of thefollowers. 'Ihe high points of the y`"cam surface throughout the entire longitudinal extent ofthe cam fall along the line 58, and the lowpoints along the line 51. The configuration of the cam surface from the line 51 to the line 58,

7o going in the direction of the arrow, is such as to impart a uniform rotary motion to the gear 25 as the follower wheel 3| moves from the line A57| to the line 58.

As the follower 3| moves from its low point on the line -51 -to itshigh point on the line 58,

it does work and drives its respective gear 25 through its overriding clutch. As the cam follower 3| returns from its high point on line 58 to its low point on line 51, it retracts its overriding clutch, the follower being held against the cam surface by its spring 46.

The configuration of the cam surface and the mounting of the cam followers are so arranged as to obtain an overlapping driving action. It will thus be seen from an examination of Fig. 4 that the follower, indicated by A, will pass the line 51 before the follower, indicated by B, reaches the line 58. Thus the follower A will take up its load before B releases its share of the load. This provides a continuous driving action, eliminating driving shock and greatly improving the smoothness of the drive even after the parts have become worn.

For yieldably holding the followers 3| against the cam surface in all positions of rotation of the followers and of axial movement of the cam 4|), each is provided with a spring 46 secured to a pin A41 aiilxed to the follower arm 30. The other end of spring 46 is secured to a peg 48 affixed in the casing I4. The casing I4 is provided with recesses 44 through which the follower arms` 30 and follower Wheels 3| may project. If desired, to improve the engagement between the rollers 3| and the inclined parts of the cam surface, the edges of the rollers 3| maybe rounded.

In operation, as the drive shaft VI 8 rotates in the direction of 'the arrow, the casing I4 revolves, causing the driven shaft 2| to rotate at the same speed and in the same direction as the drive shaft, when 'the rollers 3| Vare on the step 4| where the cam surface is truly concentric as represented by the line Y55 in Fig. 4. No reciprocating motion takes place in the followers or in the three-roll overriding clutches at this time.

As the cam 46 is moved longitudinally so that an inclined part of the cam surface engages the rollers 3|, the contour of the cam surface imparts a reciprocating motion to the followers which causes the driven shaft to rotate in the same direction as the drive shaft I8 and the casing I4, but at an increased speed. Thus, this speed may be increased by infinitely small amounts, depending upon the axial position of the cam 4i) until the followers 3| engage the step 43 where maximum speed for the driven shaft 2| is reached. An overdriving action is thereby obtained between the drive shaft I8 and the driven shaft 2|.

It Will be noted, particularly from Fig. 4, that, as the casing I 4 rotates, the follower arms 3|), rotating in the direction of the arrows, push the rollers 3| along the cam surface. If desired, the mechanism may be so arranged that the follower arms 3|] pull the rollers 3| along the cam surface.

Obviously, any number of steps may be provided on the cam 4|), or, if desired, no steps may be prof vided, the cam being continuously inclined from one end to the other. Or, if desired, the cam may have but a single step with no provision for variation of speed ratio.

Referring now to Figs. 5, 6 and '1, the stationary housing 6!) comprises Aa generally cylindrical body 6| with detachable heads or ends 62 and 63. Here the drive shaft 64 carries a drum type cam 65. The drive shaft v64 is journalled in a roller bearing 66 carried by the head 62 and in a roller bearing 61 carried .by an intermediate support 8|).

The cam 6.5 has the same general shape of cam surface as the cam in Fig. 1 and its rotation serves to -oscillate the follower arms 82 carrying the follower wheels 83. Each follower is mounted upon a longitudinal shaft 68 mounted in the stationary casing. Each shaft 60 is journalled by bearing 69 in head 62 and by roller bearing 1| in support 80 and by roller bearing 10 in head 63.

Each follower 82Mhasa square bore in its hub by which it is slidably mounted on its respective square shaft 68.

`Oscillation of each shaft 68 drives a gear 12 i through an overriding three-roll clutch similar to 10 that forming part of gear 25 in Fig. 3. Here the ,core.14 is secured` to shaft 68 and carries the tapered recesses 15 within which are held the rolls l 16. These rolls are wedged into the tapered remounted upon the driven shaft 81.

Each gear 12 meshes with a single gear 98 Driven shaft 81 is journalled in stationary support 80 by roller bearing 88 and in the head 63 by roller bearing 89.

Oscillation of the followers 82 causes the overriding clutches to drive gears 12 which in turn drive gear 90 continuously in a single direction.

For yieldably holding the followers 83 against the cam surface of cam 65, each shaft 68 is provided rwith an arm 84 axially fixed in position. The arm 84 is connected to a coil spring 85 which is connected to a peg 86 secured to the head 62.

For changing speed, provision is made for simultaneously shifting the followers 83 axially to engage different parts of the cam 65. The shifting mechanism comprises an annular drum 93 slidably mounted Within the body 6| of the housing and having a pair of pins 95 projecting out `through longitudinal recesses 96.

The ring 93 carries two sets of ears 94 engaging opposite sides of the follower arms 82 and encircling shaft 6|,

l but with a clearance hole to permit free rotation of the shaft.

The ring 93 is shifted by suitable external mechanism (not shown). This mechanism will be-connected to the pins 95 and will move the ring 93 and followers axially, causing the followers to engage the different steps and inclined parts of "the cam surface to obtain different speed ratios.

` would be obtained by the step |00.

"steps |00, and |02. l to zero throw of the cam followers.

represented by the line |03 in Fig. '1. The line |04 As` stated above, the surface of cam 65 is constructed on the same principle as the surface of I-Iere, however, the cam is provided with The step |02 corresponds This point is cam 40.

i motion imparted to the overriding clutches and consequently the driven shaft 81 is `at rest. When the followers 83 are moved toward the eccentric section of the cam, the followers 83 and arms 82 rockback and forth, depending upon the amount of throw of that particular section of the cam.

VThe oscillation of the cam and followers oscillates the square shaft 68, which in turn drive the "gears 12 through the overriding clutches. As the followers 83 move'from a low position along the line |06 to a high position along the line |05, the overriding clutches .engage to drive the gear 90 and driven shaft 81. The driven shaft 81 will rotate in a direction opposite to that of the drive shaft 64.

By adjusting the ring 93 axially of the housing, an iniinitelyvariable speed ratio is obtained between zero speed of the driven shaft 81 and maximum speed. The followers are held against the cam surface during their return stroke from the high point |05 to the low point |06 by the springs 85, during which time the overriding clutch of the particular follower is retracted.

'Ihe relation between the cam surface and cam followers in this case is such as to obtain the overriding cam action obtained in the first modiiication, as explained above. Each follower takes up its share of the load before the preceding follower releases its share of the load.

In Fig. 5, it will be noted that the driven shaft 81 rotates oppositely from the drive shaft 64. By reversing the cam 65 end for end, the drive shaft maybe revolved in the same direction as the driven shaft. In other words, the drive shaft, by changing the cam, can operate in either direction, but the driven shaft always operates in the same direction due to the frictional characteristics of the overriding clutches.

It will be noted, particularly from Fig. 7, that, as the cam 65 rotates in the direction of the arrow, it exerts a pushing action `on follower arms 62 as the rollers 83 roll along the cam surface. If desired, the mechanism may be so arranged that the follower arms trail the cam surface with the rotation of the cam exerting a pulling action on the follower arms 82.

Thus, a type of transmission has been described which is rugged in construction and simple in operation. The overlapping cam action in either form above described provides smooth operation. Furthermore, by axially displacing the cam surface with respect to its followers, the speed ratio may be infinitely varied. In addition, due to the shape of the cam surface, uniform rotary motion may be given to the driven shaft when the drive shaft is rotated.

It will, of course, be understood that in each of the above described modifications, suitable counterweights (not shown) will be used to place all rotary parts in both static and dynamic balance so as to reduce vibration to a minimum.

While certain novel features of the invention have been disclosed and are pointed out in the annexed claim, it will be understood that various omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

In a cam and follower mechanism, an operatively stationary, sleeve cam member having an internal cam surface, said surface comprising a follower-raising portion and a follower-releasing portion constituting together the entire operating surface of the cam, an internal rotary member within said sleeve member, a pair of cam followers pivoted to said rotary member and engaging said cam surface at points spaced substantially 180 apart, said follower-raising portion extending through an angle greater than 180 from its low point to its high point, whereby each follower picks up its load before the other follower gives up its load.

WILLIAM H. JOHNSON. 

